The free “IBM Integration Bus for Developers. fully licensed software, at no charge”. It includes “IBM WebSphere MQ” and is by this a valuable free GUI tool for developers to play with MQTT Protocol. E.g. to explore how “Last Will and Testament” messaging works.

Experts told me: It is easy to code a service to collect data in a single data format and single data protocol ( e.g. a web service ), but if you add other protocols and need data transformation, you are stuck. An ESB is the alternative: By filters, parsers and import modules, an ESB may collect data in any format and transform the data to any other format.

It is imporant to find the right position for an ESB in a manufacution environment:

A PLC on the shop floor which can process and transform multiple communication protocols, has sort of ESB functionality.

Some see an ESB on the level of a MES system, or even between MES and enterprise software.

In an infrastructure without PLCs, the ESB might be even in the “Cloud” and collect and process all messages from IOT devices.